Nexen kaak tyres

Bought Kia Cerato Koup came fitted with Nexen tires drove with that car for a year one day took the car for balancing yoh when i got there the tyres had so much Cracks inside it was bad all four of them, told kia fountains about the problem they directed me back to nexen and mintys went to get my tires changed factory fault they said and after the new fittings in 3 months tires had cracks again had them changed even the ones that i am driving with have cracks took them back they told me that they don't change anymore, how can tires have so much cracks though without any help from the manufacture kaak tyres Nexen **** **** tyres keep away from that kaak NEXEN.